Proteins that function in association with DNA have been extensively investigated in prokaryotic and eukaryotic systems because of their possible regulatory roles. We have used the technique of affinity chromatography on DNA-cellulose to isolate a class of DNA-binding proteins from human serum. These proteins appear to be unique among the serum proteins and comprise a significant fraction (1.5%) of these proteins. We propose to determine the physiological function(s) of the DNA-binding proteins by a combination of biochemical and clinical studies. Our first objective is to characterize the two major DNA-binding protein species. This characterization will include: purification of the proteins to homogeneity; determination of physical and chemical properties such as size, subunit composition, etc.; determination of substrate specificity using a nitrocellulose membrane filter assay; determination of function including the use of an in vitro transcription system using human chromatin as template; application of these procedures to any of the minor DNA-binding protein species that give evidence of importance as to function or possible role as diagnostic indicator. Our second objective is to continue a clinical screen to ascertain the significance of alterations in DNA-binding proteins. The serum of individuals with various pathological disorders will be examined for modulations in the levels of the minor DNA-binding protein species; the initial emphasis will be on patients with different malignant diseases. To facilitate the screen of such proteins, a radioimmuno or radial diffusion assay will be developed for each of the DNA-binding proteins with proven potential as possible diagnostic and/or prognostic indicators. The serum of normal individuals will be examined for genetic polymorphism of the major DNA-binding proteins.